Wrapping a three month murder trial that cost millions and captured unprecedented public interest earlier this month former Northern Territory Supreme Court Chief Justice Brian Martin found Mr Rayney not guilty of his wife's murder.

Mrs Rayney – a Supreme Court of WA registrar - disappeared on August 8, 2007 after leaving her weekly boot scooting class. Her body was found a week later in a shallow Kings Park grave, sparking a mystery that would plague WA for more than half a decade.

Speaking outside court moments later Mr Rayney said his two daughters still had no answers for what happened to their mother.

"This is an extremely hard thing for my family to accept," he said.

That afternoon Mr Rayney celebrated with a gathering at the Como home the couple had shared, also, according to Justice Martin's decision, the scene of Mrs Rayney's attack.

Few in the WA legal fraternity had expected an appeal, according to Australian Lawyers Alliance WA president Tom Percy QC.

"The general consensus in the legal community at the moment is one of shock and surprise," he said on Thursday moments after the New South Wales DPP – tasked with the Rayney prosecution – revealed it had filed an application for leave to appeal.

"Whilst we always knew it was a possibility I don't think that anyone thought that it was a realistic possibility.

"The judgment to me seemed one which was very sound in law and one which was very comprehensive in fact."

The prosecution had laid down three draft grounds on which is has sought to appeal, the Supreme Court of WA confirmed.

Nobody was more surprised by the state's decision to appeal than Mr Rayney's legal team.

His lawyer Laura Willox (nee Timpano) said although the decision had come as a "surprise" she was "not troubled" by the grounds of appeal.

"Whether the prosecution will even be given leave to appeal is a matter for the courts," she said.

The prosecution's application for leave to appeal would now be assessed by a Court of Appeal justice and, if that justice is satisfied they have merit, an appeal would then be heard by a Court of Appeal panel of justices.

"Whether or not there will have to be an independent judge brought in to hear the application for leave is a matter that will have to be resolved by the Supreme Court," Mr Percy said.

And the prospect of a retrial would still be "a long way off," he said.

Mr Percy said a defamation case launched by Mr Rayney against the WA Government, which was put on hold pending the outcome of the murder trial, would likely be stalled again by the appeal.

Mr Rayney's ability to practise as a lawyer again also remains in doubt with both the Legal Practice Board and Barristers' Board reviewing Mr Rayney's privilege to practise law before the appeal was launched.